Allow perfetto traced_probes to access tracefs on user
Allows the traced_probes daemon to access the core ftrace
functionalities on user builds. Specifically this involves:
- Whitelisting the per_cpu/ subdirectory to access:
1) trace_pipe_raw file to allow perfetto to read the raw
ftrace buffer (rather than the text-based /trace endpoint)
2) cpuX/stats and cpuX/buffer_size_kb that allow to
tune the buffer size per-cpu pipe and to get basic
statistics about the ftrace buffer (#events, overruns)
- Whitelistiing the full event directories rather than the
/enable files. This gives also access to the /format files
for the events that are already enabled on user builds.
/format files simply describe the memory layout
of the binary logs. Example: https://ghostbin.com/paste/f8m4k
This still does NOT allow enabling the events labeled as
"_debug" (mostly events that return activity on inodes).
We'll deal with that separately as soon as we get a POC
of inode resolution and a sensible blacklist/whitelist model.
Bug: 70942310
Change-Id: Ic15cca0a9d7bc0e45aa48097a94eadef44c333f8
3 files changed